WASHINGTON, DC - DECEMBER 21: Robert Groves, Director of the U.S. Census Bureau, releases the first results of the 2010 Census during a press conference December 21, 2010 in Washington, DC. The population of the United States was listed at 308,745,538, which calculated to a 9.7% increase, the slowest rate of growth since the Great Depression.

California grew by a smaller percentage over the past decade than at any time since it became a state in 1850, meaning it will not gain any new seats in the House of Representatives for the first time in 90 years, U.S. Census Bureau figures show.

The numbers, released Tuesday in the unveiling of the bureau's 2010 decennial population tally, conflict with a recent, higher count by the state that would have netted California two more congressional representatives.

"California has always had a growing piece of the pie, and this is the first time we haven't had that," Johnson said. "That's certainly going to disappoint some people."

The Census Bureau has California's head count at 37,253,956, which still makes it the most populous state in the nation. The total is 10 percent more than the 2000 census count of 33,871,648.

Dueling counts

Earlier this month, however, the state Department of Finance placed California's population at 38.8 million. The department uses different criteria for tallying than the Census Bureau does, measuring housing, tax, school and other data as opposed to the bureau's primary method of sending questionnaires to households.

California's total of House representatives would have gone up from the current 53 to 55 under the Department of Finance's figures.

Any hope of ratcheting the census count up to meet state numbers is in vain, however, according to Department of Finance spokesman H.D. Palmer. The U.S. Supreme Court ruled in a lawsuit challenging the 2000 census that the bureau's figures are final, so California will just have to live with the lower number, he said.

First since 1920

Before this year, California had gained at least one new House seat after every census except the one in 1920, when Congress could not agree on a reapportionment.

The Census Bureau will release more big salvos of figures from February to April, giving breakdowns by county, city and block, as well as gender and racial categories. More releases will follow through 2012.

The new figures have a significant effect not just in determining the number of congressional representatives each state has, but how each draws its legislative lines.

In California, next year will be the first time federal and state districts are set by the state Citizens Redistricting Commission, which voters created to take reapportionment out of the hands of the Legislature. The Bay Area, which has grown slowly in recent years, may not fare well.

"We think the inland regions have been growing fastest in the state, so there could be some gains there and losses in the coastal regions," Johnson said. "But again, we have to wait to see what the more detailed numbers show."

Slowdown theories

Johnson said the new federal count suggests that without migration into California from Asia and Latin America, the state's population total might have actually shrunk over the past decade.

"It's really about the domestic migration flow," he said. "The Department of Finance estimated we lost about 200,000 people to other states, but the census presumes we lost about 1 million people to other states. So we almost certainly gained population through international migration."

About half of California's immigrants come from Latin America, mainly Mexico, he said. A third come from Asia, mainly China, the Philippines and India, and the remainder come primarily from Canada and Europe.

Some demographers from organizations including the Brookings Institution blamed the population slowdown at least in part on the bad economy, but the state's main head-counting organization disagreed.

"When you're in the midst of an economic downturn, as we have been for some time, there is a tendency to stay where you are, not leave," Palmer said.

U.S. grew slowly

The U.S. population overall is set at 308,745,538, Census Bureau Director Robert Groves said. That represents a growth of 9.7 percent - virtually the same as California's - from the 2000 census count.

It was the slowest growth rate in America since the Depression-ravaged 1930s, when the population grew 7.3 percent, Groves said. However, he did not attribute the current slowdown to the recession, saying only that other developed countries have also seen slowdowns in population growth.

Although blue-state California is standing pat in its federal representation, the full political fallout for the country was more dramatically to the right.

Regionally, the red-leaning South saw the biggest population increase, with 14.3 million new residents. That boom was led by Texas, where 4.3 million new residents earned the state four new congressional representatives, giving it a total of 36.

Asked if his crews might have undercounted some areas, such as California, Groves responded: "The census, as much as we can know, is complete."

Census tidbits

Facts from the 2010 U.S. census:

New Jersey has the most people per square mile, 1,195.5. Alaska has the fewest, 1.2. California has 239.1, and the United States as a whole has 87.4.

Nevada grew the most over the past decade, 35.1 percent, followed by Arizona, Utah, Idaho and Texas.

Michigan was the only state to lose population. Its total dropped 0.6 percent. The slowest-growing states were Rhode Island, Louisiana, Ohio and New York.

In 1910, 7.7 percent of the nation's population was in the West. That has now grown to 22.5 percent.